The present invention is directed to a fixed angle ultracentrifuge rotor and, more particularly, is directed to a fixed angle rotor having a fluid containment annulus formed in it to retain any spilled or excess fluid from the centrifuge tubes in the rotor.
In most presently used fixed angle rotors, a plurality of centrifuge tube cavities are formed in an annular arrangement about the center of the rotor. These cavities are oriented at some acute angle to the spin axis of the rotor and are designed to receive a plurality of sample carrying centrifuge tubes. The angled orientation of the tubes permits the density gradient bands to be relatively narrow while, at the same time, a tube cap on the tubes is generally not required if the proper amount of fluid has been placed in the tube. However, in some instances it may be desirable to put tube caps on the tubes to retain the fluid within the tubes in case too much fluid has been placed within the tubes.
As more research is conducted into the areas of pathogenic and radioactive substances, it is more and more important to maintain the cleanliness of the overall centrifuge, including the rotor chamber in the centrifuge. This is necessary in order to protect the users of the centrifuge who are running these critical experimental research investigations of various hazardous materials. Quite often in presently used fixed angle rotors the tube is placed within the rotor with a lid placed on the rotor covering the cavity areas of the rotor containing the tubes. Since the tubes are oriented at an acute angle with respect to the spin axis, the tubes should not be filled completely to their top edge with any fluid sample because, during centrifugation, the surface level of the fluid will reoirent and may be directed out of the tube if no cap is located on the tube or, if a tube cap is used, may force the cap to be separated from the tube during centrifugation. Although there are instructions that a tube should be filled only to a certain level, in practice the operators of the centrifuges have difficulty in placing the proper amount of fluid in the tube. Many times the tube is inadvertently filled to a slightly larger volume than it should for use in a particular fixed angle rotor.
As a result, fluid will escape from the uncapped centrifuge tubes and collect in the area of the rotor above the centrifuge tube cavities. As a result, during centrifugation, pressure will be exerted on the rotor lid by this fluid as a result of centrifugally induced forces, causing a potential leakage of the fluid into the rotor chamber. If the rotor contains a hazardous material, a problem can arise, since, once the centrifugation run is completed and the operator opens the centrifuge rotor chamber, he may be exposed to some possible hazardous material if it has escaped the rotor. Therefore, it is important to be able to contain any excess fluid which may escape from the tube or the tube cavity during centrifugation, within the rotor itself. Also, there is the concern with respect to aerosoling of various hazardous materials. For a more detailed description of the particular hazards of centrifugally induced aerosoling of a fluid sample, attention is directed to co-pending patent application Ser. No. 164,877, filed July 1, 1980 by Mark J. Cowell and Thomas D Sharples.
It is important that the excess fluid not exert a pressure on the rotor lid as a result of centrifugally induced forces on the rotor lid since the seal between the rotor lid and the rotor body will in some instances be incapable of maintaining its proper seal when operating at very high centrifuge speeds.